Method for treating metal



Nov. 20, 1923. 1,474,953

R. E. BRADLEY ET AL METHOD FOR TREATING METAL Filed Ju ne 1'7. 1922 y E m m J a Z "W. mg

Patented I Nov. 923,

UNITED STATES v 1,414,953 PATENT OFFICE;

BOSS EDWARD BRADLEY. AND CHARLES RAYMOND WEBBER, OF BALTIMORE, MARY- LAND,".ASSIG,NORS T BALTIMORE 'ruim' COMPANY,

LAND, a CORPORATION or vmcmm;

INQ, BALTIMORE, MARY- METHOD roa TREATING METAL.-

Application filed June 17, 1922. Serial N0. 568,924.

' To all whomit may concern: 5

Be it known that We, Ross EnwARD BRAD- limit and CHARLES RAYMOND l/VEBBER, residents": of Baltimore, 3 county 1 of Baltimore,

' 1 State ofMaryla-nd, have invented a new and j V useful :Method for-Treating Metal, of which the following is aspecification.

Qur'invention relates to improvementsin iinethod and "g'mean's, for" the treatment of metal bodies-composed of copper or brass, or"

i Qf DJiafi'ected-bysuchtreatment, thereby preserving to" each part :the characteristics fwhi'chespeciallyquali es-it for the serv ce requiredlofsuch part. 1 y y It is well known-that' brass and copper 'tube's of c rtain uni-form-Qgrain structure give longer life in service than; thertubes. This grain struct-urej is obtained ordinarily by annealing. in an g annealing furnace the r tube, which has"been'previously hard drawn. vThe annealing furnace,-which is usually oil fired, but in some ;.'ases heated by other heat;- 7 ing mediums,-,; gives very erratic results so far asnniform grain structiire -is concerned;

' invention, anv electric. currentie passed through, that .portionoffthe metal body only, the structure of, which. I it is desired to i change or 'modify.:, .f-Thisfis vaccom'plished by attach ing the terminals to certain points on the-body, so that only theintervenmg space between said'points'shall'be affected-by passing the cnrrentitherethrough, Thetime, .irmpera voltag'eyand cycle of alternation,

where a ternating current is used,- are accurately regulated withfre'spect-to the/crosssection-andcompositionof the portion of fm'etal body treated, and recrystallization des'ired. The'passage'of the electricjcurrent through i the," metal 'body treated,-causes a thermal expansion of the metal. This thermal expansion of the metal body is prefer;

ably utilized for automatically determining the time of'current flow. This automatic expansion control may therefore be utilized,

' Byfthe'method comprised in the present in combination with the proper regulation of amperage, voltage, etc. so that a complete recrystallization, to the predetermined grain size between the points ofconnection, 4

can be effected.

In other words, by a proper corelatio of the coefficient of expansion of the metal body, under given conditions of voltage, amperage, cycle, etc. it is possible'to utilize the said expansion after'a predetermined period of said current flow, automatically to break the current, and the predetermined period ma be adjusted to secure the grain structure esired. v

It will thusbe seenthat upon the predetermined ex'pansion may be'accurately corelated these factors; amperage, voltage, cycle of alternation, cross-section of metal .bod

7 and tune Of current The invention'is peculiarly applicable to the treatmentof brass or admiralty tubes for condensers. By locating the terminals at specific points on. the tube extension, it is possible to eliminate what is known as necking or crushin of the tube, when acki'ng inthe crown s eet of the'c'ondenser.

t is possible by this method to leave the ends, where the packing is applied ofsuf- 'fici'ent hardness, or, ent rely hard, to resist this crushing action, and at the same time to effect a complete reformation, as to size an(l*a-rrangement of the grain of the metal between said points.

Referring to the drawing,

which represents, merely by way of'exainple, suitable ,means for effecting our invention; Fig, 1 1s a, view in elevation;

Fig. "2 is, a cross-section on line 2, 2 of Fig. 1 on an enlarged scale;

Fig. 3 is a view made from a micro-photo graph of a section "of the metal before treat ment Fig.

4 is a similar view showing the granular formation, after treatment in accordancewith our invention.

Similar numerals refer to similar parts throughout the severalviews. i

The following is a specific example of "the treatment of a brass. tube in accordance with our invention.

The tube 5, which is 17.0 feet long, and {3 "inches in diameter, with a -.050 inch thick wall, is secured in'theclamp brackets 6 and 7. The brackets 6 and? are'conneeted to the bus bars 8 and 9 which are connected through the switch board 10 with the trans former 11. The clamping bracket 6 has a fixed relationship with bus bar 8, while clamping bracket 7 has a movable relationship with bus bar 9. The tube 5 which is to be treated is clamped in brackets 6 and 7 with its ends projecting beyond said brackets. The switch board 10, is provided with a number of switches Or controllers'13, for controlling, and the several meters 14, for indicating the character of current flow. The current is also controlled by an automatic circuit breaker, as at 15. This circuitbreaker is provided with coils 16 connected to contacts 17 adapted to be bridged by the circuit.

bridge 18 on frame 19 connected to the movable clamp bracket 7.

In operation: The tube is clamped in position, as above indicated, with the movable clamo bracket so positioned with respect to the contacts 17, as to require an exact predetermined movement of the bracket, due to the thermal expansion of thetube, to cause the bridging of the contacts 17.

The circuit is then closed,-with the section or extension of tube 5, between points or brackets 6 and 7, acting as a resister in said The current is so controlled by the usual controlling devices, as to ma ntain it at approximately 3250 amperes,'32 volts, 25 cycles; the time of treatment required is from five to six seconds and the temperature of the tube approximately 800 F.

As a result of these factors the tube of form and character above specified will have an expansion of approximately 1% inches between the initial positions of brackets 6 and 7. This will cause at the moment of required expansion, the movement of bracket 7, sufficient tobridge the contacts 17, where- 'upon the circuit is interruptedand the process of treatment is completed.

As the result of such treatment, the part of the tube, extending between points 6 and 7, will become perfectly uniform and homoneous in grain structure, as indicated in ig. 4, and of maximum cohesion, resulting in a tough and malleable body adapted to give the greatest possible service as a condenser tube, while the end extensions of tube 5 beyond, or outside of the points 6 and 7,

will remain hard, that is, unaffected by the current, so as to resist the necking or crashin stresses when packing in the crown sheet.

hat we claim is v a 1. The method of treating tubes composed of copper or the alloys of copper,

.as specified, and co-relating the expansion- .-which consists in subjecting the same to an electric current, under relative conditions of voltage and amperage substantially of the metal treated, and the period of current flow, substantially as described.

2. The mcthod of treating tubes composed of copper or the alloys of copper, which consists in subjecting the samebetween points removed from its two ends toan electric current, under relative conditions of voltage and amperage substantially as specified, and co-relating the expansion of the metal treated, and the period of current flow, substantially as described.

3. The method of treating tubes composed of copper or the alloys of copper, which consists in subjecting the same to an electric current, under relative conditions of voltage, amperage and cycle, substantially as specified, and co-relating the expansion of the metal treated, and the period of current flow, substantially as described.

4. The method of treating tubes composed of copper or the alloys of copper, which consists in subjecting the same to an electric and amperage substantially as specified,

and utilizing the direct action of said expansion, after a predetermined period of isiaid current flow, to interrupt said current 6. The method of treating tubes of copper or the alloys of copper, which consists in subjecting the same toan electric current, and co-relating the expansion of the metal body, under conditions f voltage and amperage substantially as specified, and utilizing the direct action of said expension, after a predetermined period of said current flow, to interrupt said current flow. and adjusting said-predetermined period of flow in order to secure the grain structure desired.

7. The method oftreating tubes of copper or the alloys of copper, which consists in subjecting the same to an electric current of approximately 3250 amperes, 32 volts and 25 cycles, and co-relating the content and expansion of the metal body, and utilizing the direct action of said expansion, after a predetermined period of said current flow to interrupt said current flow, and adjusting said predetermined period of flow in order to secure the grain structure desired.

ROSS EDWARD BRADLEY. CHARLES RAYMOND WEBBER. 

